A prototype for converting linear programming (LP) models to structured modeling graphs

Geoffrion's structured modeling provides a very promising framework for the development of future model management systems (MMS) . This thesis presents a prototype that converts a mathematical representation of simple LP models to Geoffrion's structured modeling representations. The general procedures presented could be extended to convert an LP model represented in any precisely defined mathematical language. This would allow the development of integrated modeling environments based upon the structured modeling framework which would accept input in a number of common LP language formats.http://archive.org/details/prototypeforconv00hillLieutenant, United States Coast GuardApproved for public release; distribution is unlimited

Effects of Auto-Servo Ventilation on Patients with Sleep-Disordered Breathing, Stable Systolic Heart Failure and Concomitant Diastolic Dysfunction: Subanalysis of a Randomized Controlled Trial

Background: Systolic heart failure (HF) is frequently accompanied by diastolic dysfunction and sleep-disordered breathing (SDB). Objectives: The objective of this subset analysis was to determine effect sizes of auto-servo ventilation (ASV and biphasic positive airway pressure ASV) on echocardiographic measures of diastolic function in patients with systolic HF and SDB. Methods: Thirty-two patients with stable systolic HF, concomitant diastolic dysfunction [age 66 ± 9 years old, left ventricular (LV) ejection fraction: 30 ± 7% and New York Heart Association class II: 72%] and SDB (apnea-hypopnea index, AHI: 48 ± 19/h; 53% had predominantly obstructive sleep apnea) receiving either ASV (n = 19) or optimal medical treatment (control, n = 13) were analyzed in a randomized controlled clinical trial. Polysomnographic and echocardiographic measurements were obtained at baseline and after 12 weeks. Results: AHI significantly improved in the ASV group compared to the control group (-39 ± 18 vs. -0.2 ± 13.2/h, p < 0.001). At baseline, 24 (75%) patients had impaired LV relaxation, and 8 (25%) had a pseudo-normalized filling pattern. At the 12-week control visit, diastolic function assessed by the isovolumetric relaxation time (-10.3 ± 26.1 vs. 9.3 ± 49.1, p = 0.48) and deceleration time (-43.9 ± 88.8 vs. 12.4 ± 68.8, p = 0.40) tended to improve after ASV treatment, but did not reach statistical significance. Likewise, the proportion of patients whose diastolic dysfunction improved was nonsignificantly higher in the ASV than in the control group, respectively (37 vs. 15%, p = 0.25). Conclusions: ASV treatment efficiently abolishes SDB in patients with stable systolic HF and concomitant diastolic dysfunction, and was associated with a statistically nonsignificant improvement in measures of diastolic dysfunction. Thus, these data provide estimates of effect size and justify the evaluation of the effects of ASV on diastolic function in larger randomized controlled trials

Auto-servo ventilation in heart failure with sleep apnea -a randomized controlled trial ERJ Express

ABSTRACT We tested the hypotheses that in patients with congestive heart failure (CHF) and sleep-disordered breathing (SDB) auto-servo ventilation (ASV) improves cardiac function and quality of life. Between 3/2007 and 9/2009 patients with stable CHF (left ventricular ejection fraction, LVEF≤40%) and SDB (apnea-hypopnea index, AHI ≥20/h) were randomized to either ASV (BiPAP ASV, Philips Respironics, n=37) and optimal medical management or optimal medical management alone (n=35). Outcomes were assessed at baseline and 12 weeks. The AHI assessed with polysomnography scored in one core-lab was significantly more reduced in the ASV-group (-39±16 vs. -1±13 /hour, p&lt;0.001) with an average use of 4.5±3.0 hours/day. Both groups showed similar improvements of the primary endpoint LVEF (+3.4±5 vs. +3.5±6 %, p=0.915) assessed with echocardiography. In the ASV-group reduction of N-terminal pro brain natriuretic peptide (NT-proBNP) was significantly greater (-360±569 versus +135±625 ng/ml, p=0.010). No differences were observed between the groups in subjective quality of life. In patients with CHF and SDB ASV reduced NT-proBNP levels, but improvement of LVEF or quality of life was not greater than in the control group. Data support that such patients can be randomized in large scale long-term trials of PAP therapy versus control to determine effects on cardiovascular outcome. Wordcount Abstract (≤200): 20